Scintillation materials are used in the detection and measurement of radiation. Scintillators are composed of substances which are capable of absorbing energy given off by the fission fragments emitted by radioactive elements. The absorbed energy excites fluorescent materials contained in the scintillator, so that the fluorescent materials give off light. Such scintillators are useful in many different applications, e.g., the detedtion of radioactive mineral deposits, and the detection and measurement of radioactive contamination.
Plastics are often used as such scintillation materials. The plastic materials that have found the widest application consist of those manufactured from thermosetting plastics. These thermosetting plastics include polystyrene, polyvinyl toluene, and various acrylic polymers. The acrylic polymers are primarily employed for their cost effectiveness in fabrication of large volume scintillators.
The generation of light from these plastics is accomplished through the addition of small amounts of many different combinations of organic molecules known to have fluorescent properties of high efficiency. These molecules include p-terphenyl and naphthalene.
Hyman, Jr. U.S. Pat. No. 3,886,082, issued May 27, 1975, discloses an example of one such plastic scintillator material. The scintillator disclosed in Hyman employs acrylic polymers and copolymers as the host plastic and bis-(o-methyl styryl)benzene, perylene, tetraphenylbutadiene, diphenylanthracene, bis(phenyloxazolyl benzene), and dimethyl bis(phenyloxazolyl benzene) as the fluorescent additive.
Siegrist et al., U.S. Pat. No. 4,180,479, issued Dec. 25, 1979, discloses the use of various stilbene derivatives as fluorescent agents in scintillators.
The prior art scintillators have the disadvantage that none of the host polymers have been found suitable for use at temperatures up to and above 200.degree. C. For example, the maximum temperature of non-cross linked polyvinyl toluene is 75.degree. C.; and that of cross-linked polyvinyltoluene is 100.degree. C. The prior art polymers with the highest temperature resistance are the acrylic co-polymers, with a maximum temperature of 150.degree. C.